[glibc/release/2.35/master] x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations

[glibc/release/2.35/master] x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations

[Aurelien Jarno]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=20152a849b34abe83c702b27b7276c96b191b644

commit 20152a849b34abe83c702b27b7276c96b191b644
Author: Aurelien Jarno <aurelien@aurel32.net>
Date:   Mon Oct 3 23:16:46 2022 +0200

    x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations
    
    The AVX2 strrchr and wcsrchr implementation uses the 'blsmsk'
    instruction which belongs to the BMI1 CPU feature and the 'shrx'
    instruction, which belongs to the BMI2 CPU feature.
    
    Fixes: df7e295d18ff ("x86: Optimize {str|wcs}rchr-avx2")
    Partially resolves: BZ #29611
    
    Reviewed-by: Noah Goldstein  <goldstein.w.n@gmail.com>
    (cherry picked from commit 7e8283170c5d6805b609a040801d819e362a6292)

Diff:
---
 sysdeps/x86_64/multiarch/ifunc-avx2.h      |  1 +
 sysdeps/x86_64/multiarch/ifunc-impl-list.c | 17 ++++++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/sysdeps/x86_64/multiarch/ifunc-avx2.h b/sysdeps/x86_64/multiarch/ifunc-avx2.h
index 5cc1e4b0bc..0456fa6efe 100644
--- a/sysdeps/x86_64/multiarch/ifunc-avx2.h
+++ b/sysdeps/x86_64/multiarch/ifunc-avx2.h
@@ -30,6 +30,7 @@ IFUNC_SELECTOR (void)
   const struct cpu_features* cpu_features = __get_cpu_features ();
 
   if (CPU_FEATURE_USABLE_P (cpu_features, AVX2)
+      && CPU_FEATURE_USABLE_P (cpu_features, BMI1)
       && CPU_FEATURE_USABLE_P (cpu_features, BMI2)
       && CPU_FEATURE_USABLE_P (cpu_features, LZCNT)
       && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index a7c8ebbe85..b224e6a644 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -516,15 +516,21 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/strrchr.c.  */
   IFUNC_IMPL (i, name, strrchr,
 	      IFUNC_IMPL_ADD (array, i, strrchr,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __strrchr_avx2)
 	      IFUNC_IMPL_ADD (array, i, strrchr,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __strrchr_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, strrchr,
 			      (CPU_FEATURE_USABLE (AVX512VL)
-			       && CPU_FEATURE_USABLE (AVX512BW)),
+			       && CPU_FEATURE_USABLE (AVX512BW)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __strrchr_evex)
 	      IFUNC_IMPL_ADD (array, i, strrchr, 1, __strrchr_sse2))
 
@@ -705,15 +711,20 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
   /* Support sysdeps/x86_64/multiarch/wcsrchr.c.  */
   IFUNC_IMPL (i, name, wcsrchr,
 	      IFUNC_IMPL_ADD (array, i, wcsrchr,
-			      CPU_FEATURE_USABLE (AVX2),
+			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)),
 			      __wcsrchr_avx2)
 	      IFUNC_IMPL_ADD (array, i, wcsrchr,
 			      (CPU_FEATURE_USABLE (AVX2)
+			       && CPU_FEATURE_USABLE (BMI1)
+			       && CPU_FEATURE_USABLE (BMI2)
 			       && CPU_FEATURE_USABLE (RTM)),
 			      __wcsrchr_avx2_rtm)
 	      IFUNC_IMPL_ADD (array, i, wcsrchr,
 			      (CPU_FEATURE_USABLE (AVX512VL)
 			       && CPU_FEATURE_USABLE (AVX512BW)
+			       && CPU_FEATURE_USABLE (BMI1)
 			       && CPU_FEATURE_USABLE (BMI2)),
 			      __wcsrchr_evex)
 	      IFUNC_IMPL_ADD (array, i, wcsrchr, 1, __wcsrchr_sse2))